How do I ssh from one container to a different container?

[phil-s]

https://docs.lando.dev/config/ssh.html makes it sound as if this would Just Work, with ssh keys being automatically synchronised between containers, but I'm definitely missing something, because:

• My containers don't have ssh or sshd installed at all.
• If I install them then ssh-add -l shows no keys.
• If I service ssh start on a container and try to ssh -v to it from another container, key authentication fails and it falls back to asking for passwords.

This is supposed to work, yes?

I'm trying to run a shell command on container B as part of a tool that executes on container A, and ssh is the most obvious way to do that, and it sounded like it wasn't necessary to set things up manually.